Sight for ordnance.



1 PATEIT'IEDV MAY 7, 1907.

H. C. MUSTIN & G. N.-SAGMU-LLER.

SIGHT POR ORDNA'NE.

APPLICATION FILED APR-17 ,11 906.

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NTED STATES PATENT OFFICE.

HENRY C. MUSTIN, OF WASHINGTON, DISTRICT OF COLUMBIA, AND GEORGE N. SAEGMULLER, OF ROCHESTER, NEW YORK SAID MUSTIN ASSIGN OR TO SAID SAEGMULLER.

SIGHT FOR ORDNANCE.

Patented May 7, 1907.

Application filed April 17, 1906. Serial No. 312,212.

T0 all whom it' muy concern.-

Be it known that we, HENRY C. MUsriN, residing at I/Vashington, in the District of Columbia, and GEORGE N. SAEGMULLEE, residing at Rochester, in the'county of Monroe and State of New York, both citizens of the United States, have invented certain new and useful Improvements in Sights for Ordnance; and we do hereby declare the following to be a fullclear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention consists in an illuminating attachment intended to be used at night with gun sight telescopes of that class which have reticules composed of glass or other refracting material with cross lines etched. therein.

The purpose of the invention is to illuminate a portion of the cross lines drawn or etched on the surface of glass in a compound cemented lens of a sight telescope.

The object of the invention can be explained by pointing out the defects in' other devices for illumination. For example, there is one which consists in placing in the eye piece of a telescope a glass reticule with parallel plane faces g on one of these faces cross lines are etched. The periphery of the reticule is polished and silvered except for a small portion where a pencil of light is admitted to the interior the rays of light entering the interior illuminate a portion of the cross lines directly and illuminate the other portions indirectly after successive reflections at the cylindrical mirror formed by the periphery of the reticule. The complete cross lines are thus rendered visible 3 but besides the light scattered from the cross lines p there is light from the caustics which are necessarily formed within the field, by reflection at the cylindrical surface of the periphery of the reticule, also there is light scattered from dust, or any inequalities on the faces of the reticule. All of this light is additional to the light emitted by the target or other object under observation; now it is well known that when an observer is looking at a dim object, all luminous surfaces between the object under observation and his eye are serious hindrances to his ability to see the object. But, in order that the line of sight may be I directed to the target, the observer must be l able to see the intersection of the cross lines, so there must be at least a sufficient amount of light for that purpose interposed between his eye and the target. In the case cited, there is added to this amount, a comparatively large quantity which is certain to be given by the caustics. The same defect appears in another type of illuminating device in which, instead of a reticule, there is a compound cemented lens, on one of whose cemented faces are etched the cross lines. The periphery of this compound lens is polished and silvered except for a small portion where the pencil of light is admitted to illul minate the cross lines; the caustics by re l flection at a cylindrical surface are therefore formed within the field of this telescope also, and thus the observers ability to direct the line of sight to a dim target is seriously hindered. It is evident that the efficiency of a night sight telescope will be a maximum when the intensity of light from luminous surfaces interposed between the eye and the object under observation is reduced to a minimum. To this end it is necessary to remove the caustics andto restrict the illuminated area of the lines to only that por tion of them that is required for directing the line of sight. N ow in order that the line of sight may be directed, it is necessary, as stated above, for the observer to distinguish the intersection of the cross lines the vicingiven a certain intensity of illumination per unit of area. Heretofore it has been the practice to give the cross lines or, in other types, to the cross wires or hairs a uniform illumination' over all parts of them that appear in the field. Now if the illumination per unit of area is kept constant, and the area illuminated be restricted to the vicinity of the intersection, the ability of the observer to direct the line of sight will unot be interfered with, but the total 4quantity of light sent from the lines to the observers eye Will be diminished.

The object of our invention, therefore, is to illuminate a very small portion of the intersection of cross lines, without yproducing luminous areas that would be a hindrance to the ability of an observer to distinguish in the field of the telescopes any caustics or ity of the intersection must therefore be IOO a dim target or other object; the area illul out disturbing the optical adjustment` ol' minated in the vicinity of the intersection of the lines or wires is made so small that, although the intersection is distinct, the hindrance from this interposed luminous area is negligible. Vile will now describe our means of accomplishing this in the case ol a sight telescope in which there are etched cross lines on one of the cemented faces of a ecmpound lield lens.

A small pencil of approximately parallel rays oi light trom the rear, is thrown on the rear face oi the field lens at such an angle that the axis of the pencil, after refraction at this tace, makes as small an angle with the axis ci the eye piece as is practicable. The direction oit the pencil, inside the 'field lens, is such that its path crosses and thus illuminates the intersection oi the cross lines. The pencil after emergence from the liront face of the field lens proceeds to a portion of the telescope tube that is obscured from the eye oi the observer. There is of course a partial reflection at the rear tace of the 'held lens where the pencil enters; but these partially reflected rays proceed to a recess in the tube which is obscured from the eye ci the observer. `he partial reflection at the iront face oi the 'field lens when the pencil emerges, is negligible for the incident light is very nearly normal to the surface at this point. In consequence oi this arrangement only a small amount of light is thrown on the intersecting lines, and this light is suilicient only for the purpose of illuminating the vicinity of the intersection oi those lines, and it does not subsequently appreciably al'lect the clearness ol the object. y 7This invention will be understood by relierence to the accompanying drawing, which represents a central vertical section through the eye piece end ell a sight telescope and shows the illuminating attachment partly in section and partly in elevation.

In the drawing the eye piece end oli the telescope only is shown, as the other parts oi the telescope are well known in the art and do not constitute a part of tlns invention.

A represents the main telescope tube in which is mounted the sleeve B, which carries the compound 'lield lens which is composed of the plane glass plate C cemented to the lens C?. Etched on the tace oi this plate C or on the face ci the lens C2, where the two faces abut, are the ordinary intersecting lines, which correspond to cross hairs. These lines are well known and are not shown in the drawings. To keep the outer suriace of the plate and lens iree from dust, openings aO and bo are provided, which are closed by suitable shutters a and b, These shutters may be removed and the liace oi the lens or plate may be brushed o'fl with a suitable brush inn l serted through the opening; thus, whenever necessary, the held lens may be cleaned withthe telescope, and thus disturbing the relarier between the line olf bore oli the gun anx; the line ci sight.

The compound lenses E and E/ whiel pose the'eye lens combination are moume:k in

"ie sleeve ll. paris are the ring D, which is screwec into 't So far as describe the opti all old, and the invention consi applying to these old parts the improve/.i illuminating cevice which will new be describen.

F represents a socket piece, which is attached to the tele cope tube A over the opening li in the sleeve B. This socket piece projects upward as at F to 'form a holder lor the socket H of the insulating piece G, which carries asmall incandescent lamp g. This holder lW is provided with lufjto engage the elamp screw I, which is operated by the milled head lf, and thus the socket ll is clamped in its holder. Suitable ventilating holes /1 and f@ are provided to prevent excessive heating. while the current is on the lamp. The lamp socket may be moved in or out and clamped at the desired position in the holder l. whereby the amount of light thrown on the sight may be varied, as desired. ln order lo control and regulate this light we provide a ground glass plate l( secured in an opaque diaphragm K, which is screwed into the socket piece F. This diaphragm has a small perforation lt', which permits the light to pass through to the rectangular prism lil, which is mounted in the holder M, provided with screw threads m engaging i n the screw threa l s j" in the socket piece. This holder lil also carries a lens N mounted above the ogaque diaphragm N', which is perlorated at n. ,lijf this arrangement, a portion ol' the light vtrom the lamp g illuminates the ground glass plate l; since the plate is translucent and not transparent, the portion ol it uncovered by the perforation lr acts as a source et light; the intensity oi illumination oil this source will depend on the nearness of the lamp e; therefore by moving` the lamp sockel` outward the intensity of illumn'iation may he decreased. lt will, be seen that the source ol' light, the portion of the ground gl ass nneov ered by the perforation 7i?, remains always in a liked position with re'lerenee to the whole optical system, irrespective olV varying posiM tions oi thelamp. livergentpencils olI light proceeding 'from this ground glass sonrie are totally reilected by the prism ill a nd ent er the convergent lens N. The ground glass source is positioned in the principal Vlocal plane oi the lens il so that the pencils ol" light after passing through the lens N are changed 'from divergent to lmrallel. The small per-v foration a in the opaque diaphragm N limits the diameterof the pencil oi light l that enters the telescope tube. This pencil is composed oi rays approximately parallel, which proceed to the rear face of the compound :lield llO lens; here there ,is direction by refraction so that they are bent closer to the axis of the eye piece; thus the pencil L crosses the plane of the cross lines near the axis of the eye piece and illuminates the vicinity of the intersection of the lines. The rays then are refracted by the front face of the field lens and the pencil L2 proceeds toward a portion of the tube that is obscured from the eye of the observer. This portion of the tubeis lined with a dull black material, which prevents further refiection. A small part of the pencil L is reected inthe direction LO, and strikes in the recess b2, out of the range of vision. Thus a Ismall part only of the iielddens is illuminated,

and by confiningthis part to the intersection of the cross hairs or lines, as already described, the illumination is so small as not to materially impair the ability of the observer to observe faint objects. y

The advantage in using a ground glass source of' light lies in the fact mentioned above, that the illuminating pencil always enters the telescope in the same direction, no matter what may be the position of the lamp. This obviates the difficulty of placing the lamp in a certain .position with reference to the system. If the lamp alone should be used as a source of light, its filament must have a certain fixed position with reference to the system in order that the pencil will pass over the intersection of the lines. Any variation of the proper position of the lamp in such a case would move the pencil away from the intersection of the lines and said intersection would then become invisible. As these small lamps require frequent renewals, absence of the ground glass would entail a delicate adjustment each time a newlamp is put in, and by having the ground glass source of light, this is entirely avoided. Furthermore the ground glass permits the lamp to be moved in or out, irrespective vof the position of the filament, and thus permits the brightness of the illumination on the source to be varied at will. It will also be evident that if the lens lT were removed the pencil of light entering the tube would, although divergent, be of a small diameter at the point where it illuminates the cross lines. But in this variation of the attachment the portion of the cross lines illuminated would be larger than when the lens N is used as described.

It will be obvious that various other modifications might be made in the herein described apparatus, which could be used without departing from the spirit of our invention.

Having thus described our invention, what we claim is 1. In a sight for ordnance, the combination with a reticule, of means for throwing a pencil of approximately parallel rays of light on a limited portion of said reticule and at an angle to the line of sight, said means comprising an incandescent lamp and a fixed ground glass plate independent of the lamp substantially as described.

2. In a sight for ordnance, the combination with a telescope tube containing a reticule, cf means carried bysaid tube for illuminating a limited portion of said reticule, said means comprising an incandescent lamp and a fixed ground glass plate'independent of the lamp substantially as described.

3. In a sight for ordnance, the combination with a telescope tube, of a reti cule mounted in said tube, and means for throwing a pencil of approximately parallel rays of light on a portion only of said reticule, and at an angle to the line of sight, said means comprising an incandescent lamp and a fixed ground glass plate independent of the lamp substantially as described.

4. In a sight for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, means for illuminating a portion only of said reticule, said means comprising an incandescent lamp, and a fixed translucent plate independent of the lamp and means for varying the intensity of said illumination, substantially as described.

5. In a sight for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, and means for throwing an approximately parallel pencil of light on a portion only of said reticule and at an angle to the line of sight, said means comprising an incandescent lamp anda fixed ground glass plate independent of the lamp substantially as described.

6. In a sight for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, and means for throwing an approximately parallel pencil of light on a portion only of said reticule and at an angle to the line of sight, said means comprising an incandescent lamp, and a fixed translucent plate independent of the lamp with means for varying the intensity of this bundle of rays of light, substantially as described.

7. In a sight for ordnance, the combination with a telescope tube containing a reticule, of a socket piece carried by said tube, an incandescent lamp carried by said socket piece, a ground glass plate in front of said lamp and means for transmitting a limited portion of the rays of said lamp to a limited portion of said reticule, substantially as described.

8. In a sight for ordnance, the combination with a telescope tube containing a reticule, of a socket piece carried by said tube, an incandescent lamp carried by said socket piece, a ground glass plate in front of said lamp and means for transmitting a limited portion of the rays of said lamp to a limited portion of said reticule, and at an angle to the line of sight, substantially as described.

IOO

IOS

9. In a sight 'for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, and means 'for throwing an approximately parallel pencil of light on a portion only oll said reticule, comprising an incandescent lamp, a ground glass plate in front of said lamp, a series of diaphragme, a reilector, and a lens, substantiallT as described.

10. In a sight for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, and means for throwing an approximately parallel pencil of light on a portion only of said reticule, comprising an incandescent light, a ground glass plate in iront of said light a series of diaphragms, a reflector, and a lens, with means l'or Varying the intensity of the light thrown on said reticule, substantially as described.

11. In a sight for ordnance, the combination with a telescope tube containing a reticule, of a socket piece carried by said tube, an incandescent lamp carried by said socket piece, andv means for transmitting a limited portion of the rays of said lamp to a limited portion oll said reticule, comprising a series of perforated diaphragms, a reflecting prism, and a lens, substantially as described.

l2. In a sight for ordnance, the combination with a telescope tube containing a reticule, of a socket piece carried by said tube, an incandescent lamp adjustably mounted in said socket piece, and means for transmitting a limited portion of the rays of' said lamp to a limited portion ci said reticule, and at an angle to the line of sight, comprising a series of perforated diaphragms, a reflecting prism, and a lens, substantially as described.

13. In a sight for ordnance, the combination with a telescope tube, ol'l a reticule mounted in said tube, and means for throwing a bundle of parallel rays of light on a portion only of said reticule, comprising an incandescent lamp, a series ol diaphragme, a right angle prism, and a plano-convex lens, substantially as described.

14. In a sight for ordnance, the combination with a telescope tube, of a reticule mounted in said tube, and means `for throwing an approximately parallel pencil of light on a portion of said reticule, comprising an incandescent lamp, a series of diaphragniis, a reflecting prism, and a plano-convex lens, with means for Varying the intensity of the light thrown on said reticule, substantially as described.

In testimony whereof, l aliiX my signature, in presence of two witnesses.

HENRY C. lllUS'llN,

Writnesses R. M. PARKER, J. STEPHEN GIUSTA.

In testimony whereof, l. aHiX my signature, in presence of two witnesses.

GEORGE N. SAEGMUI'JIJER.

Witnesses GEORGE H. LEFFLER,

JOHN REMEIN. 

